Casing scraper



C. C. BROWN CASING SCRAPER July 20, 1954 2 Sheets-Sheet 1 Filed Aug. 161951 C. .C. Brown INVENTOR.

flTTOR/VEY July 20, 1954 Filed Aug. 16, 1951 C. C. BROWN CASING SCRAPER2 Sheets-Sheet 2 Ill A TTORNE Y Patented July 20, 1954 UNITED STATEdiidTENT OFFICE CASING SCRAPER Cicero C. Brown, Houston, Tex. ApplicationAugust 16, 1951, Serial No. 242,113

Claims.

This invention relates to an improved scraping tool for well pipes.

Such tools, commonly called casing scrapers, are employed in oil Welloperations for scraping the inner wall of a well pipe or casing in orderto remove scale, dirt, cement, and various other types of deposits andprojections from the pipe wall in order to provide a smooth surface forseating packers, plugs and other types of well tools which areconventionally employed to form a fluid-tight seal with the pipe wall.Due to the high pressures which must frequently be sealed off, it isobviously of greatest importance that the seat formed by the pipe wallbe as smooth as possible in order that the sealing tool will seat withmaximum sealing efiiciency against the pipe wall throughout the seatingarea. Also, the scrapers may be employed to clean the casing surfacefrom its upper end down to the seating area in order to remove anyprojections which might tend to tear or damage the sealing element ofthe packer or plug as it is lowered through the casing, since suchsealing elements are ordinarily constructed of relative soft ma terialssuch as rubber or the like.

The present invention has for its principal object the provision of animproved form of scraping tool which operates with maximum scrapingefliciency throughout the entire circumferential area of the pipe wall.

An important object is the provision of a scraping tool employing acombination of spring and hydraulic pressure to force the scrapingelements against the pipe wall.

A more specific object is the provision of a tool employing a pluralityof pairs of radially expandible segmental scraping elements arranged onopposite sides of the tool body, the pairs being oriented about thelongitudinal axis of the tool with respect to each other to cover theentire circumference of the pipe wall being scraped thereby.

Other and more specific objects and advantages oi the present inventionwill become apparent from the following detailed description when readin conjunction with the accompanying drawings which illustrate oneuseful embodiment in accordance with this invention.

In the drawings:

Fig. 1 is a longitudinal, partly sectional view of the scraping tool;

Fig. 2 is an elevational view of the body of the scraping tool;

Fig. 3 is a cross-sectional view along line 3-3 of Fig. 2;

Fig. 4 is a cross-sectional view along line i4 of Fig. 2;

Fig. 5 is an enlarged, generally quarter-sectional, view of theprincipal portions of the assembled tool;

Fig. 6 is a cross-sectional view along line 6-6 of Fig. 5; and

Fig. 7 is a cross-sectional view along line 7--1 of Fig. 5.

Referring to Fig. 1 of the drawings, the scraping tool, indicatedgenerally by the numeral I0 is shown inserted in a well casing C to bescraped thereby. The tool includes a body portion, designated generallyby the numeral I I, having a diameter such that it may be inserted intocasing: C with a small amount of clearance. Body II is: provided at itsupper end with an integral elongated shank portion I2 of substantiallysmaller diameter than body I I. The upper end of shank: portion 52 isprovided with an externally threaded pin I3 and body II is provided atits lower end with an internally threaded socket I4. Pin I3 and socket[4 provides means by which. the tool may be connected between sectionsof. a pipe string I 5 by which the tool may be lowered. into casing Cand operated therein. Body H! has an axial bore It extending entirelythere through and communicating with bore I I'of pipe: string, wherebyhydraulic fluid may be conducted from the surface through the tool, forpurposes: to be described hereinafter.

As shown particularly in Figs. 2, 3 and l, body II, adjacent the pointof connection of shank: portion I2, is provided with external threads48; and the lower portion of body II adjacent socket; M is provided witha second set of external! threads Iii. Intermediate the threadedportions; I8 and I9, body I I is provided with longitudinally spacedupper and lower slip-supporting sections 2%? and 2 i respectively, whichare separated by an intermediate slip-retainer section 22.

Each of the slip-supporting sections 20 and M is provided ondiametrically opposite sides thereof with a pair of elongated generallyrectangular slots 23-23 which are cut into the exterior cylindricalsurfaces of the sections over a width slightly less than the diameter ofthe sections to thereby form a pair of laterally spaced outwardlyextending flanges 24-24 along the sides of each slot. The slots in oneof the sections are oriented at an angle of with respect to the slots inthe other section. The slots in section 20 extend longitudinally fromthreaded portion I8 at its upper end to retainer section 22 at its lowerend, and the slots in section 2| extend from re-- tainer section 22 atits upper end to threaded portion I9 at its lower end. The lower end ofthreaded section I8 thereby forms a downwardlyfacing shoulder 25extending over the upper ends of the slots in section 20 and the upperend. of retainer section 22 forms an upwardly facing shoulder 26extending over the lower end of these slots. Similarly, the lower end ofretainer sec tion 22 forms a downwardly facing shoulder 21 over theupper ends of the slots in section 2! and the upper end of threadedsection 19 forms an upwardly facing shoulder 28 extending over the lowerends of the slots in section 2!. The upper and lower ends of flanges 24are cut away to provide narrow annular clearance spaces between the endsof the flanges and the respective abovementioned adjacent shoulders.

In removing metal to form slots 23, a portion is left medially of theslot to form a generally rectangular boss 29 equi-distantly spaced fromside flanges 24-24 and extending radially outwardly from the bottom wall30 of the slot to a point approximately flush with the outer ends ofslots 24-2fl. Boss 29 is made slightly shorter longitudinally thanflanges 2t2 l, the ends of the boss being equi-distant from the adjacentends of the flanges. A plurality of longitudinally spaced cylinderstl-iii are provided in boss 29, extending inwardly from the outer facethereof and communicating at their inner ends with bore i6 through fluidpassageways 32. A small cylindrical piston 33 fitted with sealing rings33a is reciprocably mounted in each of the cylinders 3 l.

A scraper slip 3G is mounted in each of the slots 23 for radial movementtherein. Slip 3 is generally rectangular in shape to provide freesliding fit in slot 23. The outer face of the slip is arcuate havingapproximately the same radius as body I i. The inner face of the slip isflat and is provided medially with a rectangular recess 35 registeringwith, and adapted to slidably receive, boss 2-9. On each side of recess35 there is provided a plurality of longitudinally spaced cylindricalrecesses 36, each adapted to receive one end of a coil compressionspring iii, .13 other end of which bears against bottom wall 30 of slot21%, springs 3? normally tending to urge the slip outwardly of slot 23.A plurality of spaced scraping teeth 38 are formed on the exterior ofslip 34,

being preferably in the form of segments of a coarse helical threadhaving a generally square cross section so that the upper and loweredges of the thread segments form sharp scraping edges.39-39 extendingsiopingly across the face of the slip. The outer face of the slip is outback at its upper and lower ends to form upwardly and downwardly facingexternal portions 110 and M, respectively, of reduced thickness.

An elongated tubular sleeve l? surrounds shank portion l2 and isinternally threaded at its lower end to screw down over threads Hi, thelower end of sleeve 52 forming an annular flange :33 which projectsbelow shoulder 25 and over reduced portions 46 or" the slips to serve asa retainer for the upper ends of the slips which are mounted in theslots in section 20, while permitting a limited amount of radial outwardmovement of the slips. The upper end of sleeve 42 is open, forming atrap for detritus which may settle out of fluid flowing up past theoutside of the tool during operation of the tool. A plurality of drainholes M are provided .through the wall of sleeve 52 just above the pointof connection of the sleeve to threads It. One or more set screws, asshown, extends through the threaded portion of sleeve 32 to firmly lockthe sleeve to body H.

A short internally threaded sleeve as is mounted over the lower end ofbody H and is adapted to be screwed upwardly on threads 19 and isprovided with an annular flange All projecting upwardly above threads isand is designed to surround the cut back portions M at the lower ends ofthe slips mounted in the slots in section 2i to serve as retainerstherefor,

functioning in this respect similarly to flange 43 of sleeve 42. One ofmore set screws d8 are employed to lock sleeve 46 firmly to body ll.

Retainer section 22 has its exterior machined to form a square. Eachface of the square is provided with transverse dove-tail groove t9, thesides of the groove tapering slightly toward one end, as best seen inFig. 2. A square keeper plate 50 is provided for attachment to each faceof the retainer section. A dove-tail tongue 5% is provided on the innerface of each keeper plate 5i! and i tapered from end-to-end tocomplement groove it. Tongue 5! extends transversely across the plateand projects slightly from opposite sides thereof. With thisconstruction it will be seen that the keeper plates may be pushed intoplace successively around. the four faces of the retainer section andeach will not only be locked to its respective face of the retainersection but will over-lap the end of the next succeeding plate and willthereby lock each other against lateral dislodgement from the faces ofthe retainer section. Each of the keeper plates is provided in thecenter thereof with a hole 52 which is tapped on its inner end toreceive a set screw 53, such as a conventional Allen-Head screw, whichmay be employed to additionally hold the keeper plates in place, afterthey have been properly assembled, by inserting a wrench through theouter ends of holes 52 in order to turn the screws 53. Each of thekeeper plates projects above and below shoulders 2'5 and ill and theprojecting portions are provided on their inner faces with horizontalrectangular recesses 56 which are designed to receive the cut baci:portions of the slips adjacent the upper and lower ends of retainersection 22 to thereby form retainers for these ends of the slips whilepermitting the desired degree of limited radial movement of the slips.

The scraping tool, constructed as described above, is operated in thefollowing manner:

The tool, connected into the string of operating pipe 55, is loweredthrough the upper end of casing C to the section of the inner surface ofthe casing which is to be scraped or cleaned. The pressure ofcoilsprings 31 will urge slips 3% outwardly against the casing surface sothat teeth 38 will be held in scraping engagement with the casingsurface and by reciprocatin operating pipe 15 longitudinally along thesection to be scraped, the edge 38 of the teeth will act to scrape thesurface of this section of the casing. However, the scale, cement, orother projections on the casing wall which it is sought to thus remove,is often suinciently hard and resistant in character, so that theoutward pressure of coil springs Bl on slips 34 will be overcome and thescraping teeth will merely slide over the surface of the material whichit is desired to remove without effectively scraping this material fromthe casing wall. To obviate this undesirable condition, a suitablehydraulic fluid, such as water, drilling mud, or the like, is pumpeddownwardly through the bore ll of operating pipe and bore N5 of thescraping tool and circulated in a generally conventional manner througha suitable opening in the lower end of the pipe string and up outsidethe string through the annular space between the tool and easing C.lf'he pressure of this circulating fluid will be exerted throughpassageways 32 against the inner ends of pistons 33 and will force thesepistons outwardly of cylinders 3! against the inner faces of slips 3:;driving the latter outwardly against the casing wall and therebysupplementing the force of springs 31.

The combination of spring and hydraulic pressure thus exerted on slips34 may be adjusted by suitable control of the hydraulic pressure toassure effective scraping of the inner surface of casing C as the toolis reciprocated in the casing. As the hydraulic fluid flows upwardlypast the outside of the tool, any detritus constituting the scrapingswhich tends to settle out of the fluid will deposit in the annular spacebetween sleeve 42 and shank portion l2, thereby preventing such detritusfrom falling back between the casing wall and the scraping elements.Liquid collect ing in the bottom of sleeve 42 will drain back into thecasing through drain holes 44.

By providing at least two sets of scraping slips, angularly orientedwith respect to each other as previously described, scraping of theentire circumferential area of easing C will be effectivelyaccomplished. It will be understood that more than two sets of scrapingslips may be employed and suitably angularly oriented with respect toeach other about the longitudinal axis of the tool to accomplish thispurpose.

It will be obvious that instead of scraping only a relatively shortsection of the casing, the entire length of the casing down to the pointat which a sealing tool is to be set may be scraped. This may beaccomplished by initiating the reciprocating scraping movement when thetool first enters the casing and continuing this movement while the toolis being lowered through the casing down to the point at which thesealing tool is to be set. In this way, the inner wall of the casing maybe smoothed all the way down to the sealing area and this will obviatetearing or abrasion of the sealing elements when the sealing tool issubsequently lowered through the casing.

It will be understood that numerous modifications and changes may bemade in the details of the illustrative embodiment within the scope ofthe appended claims without departing from the spirit of this invention.

What I claim and desire to secure by Letters Patent is:

1. A casing scraper, comprising, a tubular body insertible in a casingand having an axial bore therethrough, a plurality of circumferentiallyspaced longitudinally extending slots in the exterior of said body,arcuate scraping elements mounted in said slots for radial movementtherein, means on the body limiting outward movement of the scrapingelements in the slots, hollow bosses projecting radially from the bottomof said slots intermediate the sides of the slots and communicating withsaid axial bore, resilient means mounted on opposite sides of saidbosses in compression between the bottoms of said slots and saidscraping elements to normally urge said scraping elements outwardly intoscraping engagernent with the wall of said casing, and radiall; slidablepistons mounted in said bosses and having their outer ends thrustinglyengageable with the inner faces of said scraping elements, said pistonsbeing actuable by hydraulic pressure within said bore to intensify theoutward force on said scraping elements.

2. A casing scraper, comprising, a tubular body insertible in a casing,a plurality of longitudinally spaced pairs of slots in the exterior ofsaid body, arcuate scraping elements mounted in said slots for radialmovement therein, means mounted on the body limiting outward movement ofthe scraping elements in the slots, the members of each of said pairs ofslots and related scraping elements being disposed on diametricallyopposite sides of said body, and said pairs of slots and relatedscraping elements being angularly oriented with respect to each otherabout the longitudinal axis of said body whereby said scraping elementstogether when moved outwardly will engage substantially the entirecircumference of the wall of said casing, hollow bosses projectingradially from the bottoms of said slots intermediate the sides of theslots and communicating with the interior of the body, recesses in theinner faces of the scraping elements slidably receiving said bosses,resilient means mounted in compression between the bottoms of the slotsand said scraping elements to normally urge said scraping elementsoutwardly into scraping engagement with the wall of said casing, andmeans including radially slidable pistons in said bosses actuable byhydraulic pressure from within said body to intensify the outward forceon said scraping elements.

3. A casing scraper, comprising, a tubular body insertible in a casingand having an axial bore therethrough, a plurality of longitudinallyspaced pairs of slots in the exterior of said body, arcuate scrapingelements mounted in each of said slots for radial movement therein,means mounted on the body limiting outward movement of the scrapingelements in the slots, the members of each of said pairs of slots andtheir related scraping elements being disposed on diametrically oppositesides of said body, and said pairs of slots and related scrapingelements being angularly oriented with respect to each other about thelongitudinal axis of said body whereby said scraping elements togetherwhen moved outwardly will engage substantially the entire circumferenceof the wall of said casing, hollow bosses projecting radially from thebottoms of said slots intermediate the sides of the slots andcommunicating with said axial bore, recesses in the inner faces of thescraping elements slidably receiving said bosses, resilient meansmounted on opposite sides of said bosses in compression between thebottoms of the slots and said scraping elements to normally urge saidscraping elements outwardly into scraping engagement with the wall ofsaid casing, and radially slidable pistons mounted in said bosses andhaving their outer ends engageable with the inner faces of said scrapingelements, said pistons being actuable by hydraulic pressure within saidbore to intensify the outward force on said scraping elements.

4, A casing scraper according to claim 3 having keeper elements mountedon said body and engaging the opposite ends of said scraping elements tolimit their outward movement in said slots.

5. A casing scraper according to claim 3 wherein said scraping elementsare provided on their exterior faces with scraping teeth comprisingsegments of a helical thread formed thereon.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,623,543 Jones et al Apr. 5, 1927 1,843,668 Farmer Feb. 2,1932 1,933,595 Kapp Nov. '7, 1933 2,275,939 Baker Mar. 10, 19422,438,673 McMahan Mar. 30, 1948 2,464,390 Hammer Mar. 15, 1949 2,499,916Harris Mar. 7, 1950

